JPH0411601A - Polyvinyl alcohol polymer and its production - Google Patents

Abstract

PURPOSE:To obtain the title polymer which has excellent dispersibility, can give a homogeneous aqueous solution of a high cloud point and is useful for paper processing, textile processing, etc., by selecting a polyvinyl alcohol polymer having a specified structure and a specified degree of polymerization. CONSTITUTION:A polyvinyl alcohol polymer comprising 50mol% or above structural units of formula I, terminated with an amino group, an ammonium group or a sulfonic acid group (e.g. a group of formula II or III) and having a degree of polymerization of 3500 or below.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field The present invention relates to a polyvinyl alcohol polymer and a method for producing the same.

B. Prior Art Conventionally, polyvinyl alcohol polymers have been widely used as dispersants and surfactants. However, if the degree of saponification is lowered in order to improve the surfactant ability, there is a drawback that satisfactory dispersion performance cannot be obtained due to the equinox phenomenon of the polyvinyl alcohol polymer. Therefore, a method has conventionally been used in which the equinox point is raised by introducing a cationic group or anionic group into the side chain. However, polyvinyl alcohol-based polymers that have cationic or anionic groups in their side chains have different adsorption conditions on dispersoids compared to polyvinyl alcohol-based polymers that do not have cationic or anionic groups in their side chains. However, although an increase in the equinox point was observed, the dispersion performance was not satisfactory.

Problems to be Solved by C An object of the present invention is to provide a novel polyvinyl alcohol polymer free from the above-mentioned problems.

D. Means for Solving the Problems In view of the current situation, the inventors of the present invention have conducted intensive studies on polyvinyl alcohol polymers that have better dispersion performance and a higher equinox point. % or more, a polymerization degree of 3,500 or less, and an amino group, an ammonium group, or a sulfonic acid group at the end, and have completed the present invention.

The present invention will be explained in detail below.

The polyvinyl alcohol polymer of the present invention contains 50 mol% or more of the following structural unit A, has a degree of polymerization of 3500 or less, and has an amino group, an ammonium group, or a sulfonic acid group at the terminal.

A: -(-CH, -CH→-H Alcohol units other than the vinyl alcohol unit (structural unit A) contained in the polyvinyl alcohol polymer of the present invention include α-methyl vinyl alcohol, α-ethyl vinyl alcohol, α -Structural units consisting of brobyl vinyl alcohol, α-butyl vinyl alcohol, and α-hexynruvinyl alcohol can be mentioned.

The content of structural unit A needs to be 50 mol% or more from the point of view of the polymer's point and dispersion performance, preferably 60 mol% or more, more preferably 70 mol% or more.

There are no particular restrictions on the structural units other than the structural unit A and the above-mentioned alcohol units contained in the polyvinyl alcohol polymer of the present invention, but from the viewpoint of not lowering the equinox point of the polymer and dispersion performance, Structural unit B below
is preferred.

B: (-CH, -CH+- 0=C-R2 (Here, R1 is H or a hydrocarbon group having 1 to 20 carbon atoms.) If the number of carbon atoms in R1 is larger than the above, it is hydrophobic. This is not preferable because the chemical properties become too strong and the equinox point of the polymer decreases.

Structural unit B includes structural units consisting of vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate, and α-substituted products thereof, especially vinyl acetate. units and vinyl pivalate units are preferred.

The content of structural unit B is 50% from the viewpoint of dispersion performance and equinox.
It is necessary that the amount is less than mol%.

The polyvinyl alcohol polymer of the present invention must contain an amino group, an ammonium group, or a sulfonic acid group at the end of the polymer. From the viewpoint of dispersion performance, it is preferable that the polymer contains an amino group, an ammonium group, or a sulfonic acid group only at one end.

Specific examples of terminal groups containing an amino group or an ammonium group include the following.

and a group connecting the nitrogen atom of the quaternized group or the oxygen atom in the formula (I[I), respectively. ) Further, specific examples of the terminal group containing a sulfonic acid group include the following.

CH2CHCoo (CHz)n 503M
(Va)p! and this quaternized product and this quaternized product P and this quaternized product (where n is O~3, m is 1~10, R'', R3, R
6, R7R8 is a hydrogen atom or a methyl group, R', R5
is a lower alkyl group (which may contain a substituent); X is a negative group that forms a salt with ammonium nitrogen; L is an amino or ammonium nitrogen atom; , R10 and R11 are hydrogen atoms or methyl groups, n is 2 to 4, M is a hydrogen atom, an alkali metal or an ammonium ion, respectively.) If the number of carbon atoms in R2-R11, m and n are larger than the above, This is not preferable because the hydrophobicity becomes too strong and the equinox point of the polymer decreases.

It is essential that the polyvinyl alcohol polymer of the present invention contains the above-mentioned structural unit A, and preferably contains structural unit A and structural unit B.
There is no problem with the presence of other structural units as long as the content of A is 50 mol% or more. The structural units of the pond include, for example, ethylene, propylene, isobutyne, acrylic acid, methacrylic acid, their salts, or their alkyl esters,
Acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, ethyl vinyl ether, butyl vinyl ether, N-vinylpyrrolidone, vinyl chloride,
Examples of structural units include vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, and tetrafluoroethylene.

The degree of polymerization of the polyvinyl alcohol polymer of the present invention is preferably 3,500 or less, from the viewpoint of effectively allowing the amino group, ammonium group, or sulfonic acid group present only at one end of the polymer to act effectively. is 2000 or less, more preferably 1000 or less. The lower limit of the degree of polymerization of the polymer is not particularly limited, but is 20 or more, preferably 40 or more.

Next, a method for producing the polyvinyl alcohol polymer of the present invention will be explained.

The following two methods are known as methods for introducing amino groups, ammonium groups, or sulfonic acid groups into the terminals of polyvinyl alcohol polymers.

The first method is a method of copolymerizing a vinyl monomer having an amino group, an ammonium group, or a sulfonic acid group.

The second method is a so-called polymer reaction method, in which an amino group, an ammonium group, or a sulfonic acid group is introduced into the alcohol moiety of a polyvinyl alcohol polymer by post-modification.

However, although it is possible to introduce amino groups, ammonium groups, or sulfonic acid groups into the polymer by these methods, it is possible to selectively introduce amino groups only at the terminals of the molecules, which is a feature of the polymer of the present invention. , ammonium groups or sulfonic acid groups cannot be introduced. Under these circumstances, the present inventors investigated methods for selectively introducing amino groups, ammonium groups, or sulfonic acid groups only at the terminal ends of molecules. discovered that polyvinyl alcohol-based polymers having amino groups, ammonium groups, or sulfonic acid groups only at the ends can be obtained by polymerizing vinyl esters in the presence of a chain transfer agent having This is what I did.

The production method of the present invention is characterized by polymerizing vinyl monomers mainly composed of vinyl ester monomers such as vinyl acetate in the presence of a chain transfer agent having an amino group, an ammonium group, or a sulfonic acid group. A polyvinyl ester polymer having ammonium groups, ammonium groups, and sometimes sulfonic acid groups is produced. Next, a polymer containing structural unit A can be obtained by saponifying the polymer obtained by the above method.

The vinyl ester used in the present invention can be any vinyl ester that can be radically polymerized.

For example, vinyl formate, vinyl acetate, vinyl propionate,
Examples include vinyl pivalate, vinyl persate, vinyl laurate, and vinyl stearate, among which vinyl acetate is preferred because it has the best polymerizability. Furthermore, monomers copolymerizable with these vinyl esters can be copolymerized. For example, ethylene, propylene,
Isobutylene, acrylic acid, methacrylic acid, their salts or alkyl esters thereof, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, ethyl vinyl ether, butyl vinyl ether,
Examples include N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, and tetrafluoroethylene.

The chain transfer agent used in the present invention is not particularly limited as long as it contains an amino group, an ammonium group, or a sulfonic acid group, but among them, the following chain transfer agents are preferably used.

Specific examples of chain transfer agents containing an amino group or an ammonium group include the following.

and a group connecting the quaternized compound or ammonium nitrogen atom with the nitrogen atom of the amide group in the formula (1) or the oxygen atom in the formula (I[[), respectively. ) Specific examples of chain transfer agents containing sulfonic acid groups include the following.

R3CHz-CHCoo (Ct(-)n SO3
M (V′ b) and its quaternized product p! and its quaternized product (where n is 0 to 3, m is 1 to 10. R', R3,
R6, R'R8 are hydrogen atoms or methyl groups, R', R
5 is a lower alkyl group (which may contain a substituent), x is a negative group that forms a salt with ammonium nitrogen, L is amino (here, R11 is a lower alkyl group, Rlo, R1+
represents a hydrogen atom or a methyl group, n represents 2 to 4, and M represents a hydrogen atom, an alkali metal or an ammonium ion, respectively. ) The polymerization of vinyl monomers mainly composed of vinyl ester monomers such as vinyl acetate in the presence of a chain transfer agent having an amino group, an ammonium group, or a sulfonic acid group according to the present invention is carried out in the presence of a radical polymerization initiator, resulting in bulk polymerization. Although the polymerization can be carried out by any method such as legal polymerization, solution polymerization, pearl polymerization, or emulsion polymerization, solution polymerization using methanol as a solvent is industrially most advantageous. There are no particular limitations on the amount and method of addition of the chain transfer agent present in the polymerization system, and should be appropriately determined depending on the physical properties of the intended polyvinyl ester polymer. As the polymerization method, known methods such as batch, semi-continuous, and continuous methods can be employed.

As the radical polymerization initiator, known radical polymerization initiators such as 2.2'-azobisisobutyronitrile, benzoyl peroxide, and carbonate peroxide can be used, but 2.2'
- Azo initiators such as azobisisobutyronitrile are preferred because they are easy to handle. Furthermore, radiation, electron beams, etc. can also be used. It is desirable to adopt an appropriate polymerization temperature depending on the type of initiator used, but it is usually 30-9a.
Selected from the range of °C.

After polymerization for a predetermined period of time, unpolymerized vinyl ester monomers are removed by a conventional method to obtain a polyvinyl ester polymer having an amino group, an ammonium group, or a sulfonic acid group at the terminal end.

Next, in order to obtain a polyvinyl alcohol polymer having the structural unit A, the polyvinyl ester polymer thus obtained can be saponified by a conventional method, or the polyvinyl ester polymer can be obtained by saponifying the polyvinyl ester polymer having the structural unit A in an alcohol solution. Preferably, it is carried out as a methanol solution. Not only anhydrous alcohols but also those containing a small amount of water can be used depending on the purpose, and organic solvents such as methyl acetate and ethyl acetate may be optionally contained. Saponification temperature is usually 10-70
Selected from the range of °C. As the saponification catalyst, alkaline catalysts such as sodium hydroxide, potassium hydroxide, sodium methylate, and potassium methylate are preferable. 0. molar ratio to unit.
It is desirable to use 0.001 or more, preferably 0.002 or more. On the other hand, if the amount of alkali is too large, it will be difficult to remove the residual alkali from the polymer, and the polymer will be colored, which is undesirable, so it is desirable that the molar ratio is 0.2 or less. However, when the structural unit B is vinyl pivalate, it is preferable to increase the molar ratio and remove oxygen for saponification (L). In addition, if the polyvinyl ester polymer contains copolymerized components such as carboxyl groups and their ester groups that react with alkali catalysts and consume alkali, it is necessary to use the amount of alkali catalyst in addition to that amount. be.

After the saponification reaction, the precipitated polymer is purified by a known method, such as washing with methanol, to remove impurities such as residual alkali and alkali metal salts of acetate, and then dried to obtain a usually white powder.

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the same extent by these.

In the examples, "parts" and "%" are based on weight unless otherwise specified.

Example 1 Vinyl acetate (hereinafter abbreviated as VAc) 2 parts of BoO, 69 parts of methanol and )l S +c Hz well N
(CH-) 3CρD, 23 parts were placed in a reaction vessel, the inside was sufficiently purged with nitrogen, the external temperature was raised to 65°C, and when the internal temperature reached 60°C, 2.2°-Azohisisobutyronitrile was added. 10 parts of methanol containing 1.1 parts were added. Immediately, 50 parts of methanol containing 1 part of H3BHth-N(CH3)3C45 was added uniformly over 4 hours. The polymerization rate after 4 hours was 65%. After 4 hours, the container was cooled and the remaining VAc was expelled from the system together with methanol under reduced pressure while adding methanol to obtain a methanol solution (concentration 70%) of polyvinyl acetate (hereinafter abbreviated as PVA c). Ta. A portion of this methanol solution was taken, and the PVAc concentration was 30%, [NaO[/
C vinyl acetate units] = l), 01 (mole ratio), a methanol solution of NaOH was added and saponified at 40 °C to obtain polyvinyl alcohol (hereinafter abbreviated as PVA) with a saponification degree of 95 mol%. .

The degree of polymerization of PVA is determined by the Nakajima formula (Akio Nakajima, Kobunshi Kagaku 6451 (1949)).
), the degree of polymerization was 305.

The PVA was washed under reflux with methyl acetate containing a small amount of water, purified by Soxhlet extraction with methanol for 48 hours, dissolved in heavy water, and subjected to nuclear magnetic resonance analysis (hereinafter referred to as N
(abbreviated as MR) was performed.

This confirmed the presence of an ammonium group at the end,
Considering the polymerization mechanism, 5BH2N(
It was confirmed that the product was PVA having an ammonium group of CH3) and CQ.

The above PVAc was partially saponified to obtain a polyvinyl alcohol polymer with a saponification degree of 72 mol%. When the equinox point of this 0.4% aqueous solution was visually measured, it was 58°C.

Example 2 2800 parts of vinyl pivalate, 690 parts of methanol and H3-CH(CH3)-C00B) [2) 2-SO
After placing 0.7 parts of 3NaO in a reaction vessel and thoroughly purging the inside with nitrogen, the external temperature was raised to 65°C, and when the internal temperature reached 60°C, 20 parts of 2.2°-azohisisobutyronitrile was added. 10 parts of methanol were added. Immediately) Is CH(CL)-COOBHt'+rSOJa
50 parts of methanol containing 1.15 wJ was added uniformly over 4 hours. The polymerization rate after 4 hours was 65%. After 4 hours, the container was cooled and the remaining vinyl pivalate was expelled from the system together with methanol under reduced pressure while adding tetrahydrofuran to obtain a solution of polyvinyl pivalate in tetrahydrofuran (concentration 15%). A methanol solution of NaOH was added to a portion of this tetrahydrofuran solution so that the polyvinyl pivalate concentration was 15%, [Na0)[]/[vinyl pivalate unit] = 0.8 (molar ratio), and the solution was quenched at 40°C. PVA with a saponification degree of 98 mol% was obtained.

When the degree of polymerization of PVA was measured in the same manner as in Example 1, the degree of polymerization was 1000.

The PVA was washed under reflux with methyl acetate containing a small amount of water, purified by Soxhlet extraction with methanol for 48 hours, and then dissolved in D,-DMSO and subjected to NMR analysis. As a result, the presence of a sulfonic acid group at the terminal was confirmed, and considering the polymerization mechanism, -S -CH4-C)l 3) -C00e(:H2'
It was confirmed that it was PVA having h-8O, tea sulfonic acid groups.

The above polyvinyl pivalate was partially saponified, and the degree of saponification was 6.
A 2 mol % polyvinyl alcohol polymer was obtained. When the equinox of this 04% aqueous solution was visually measured, it was 65°C.

Example 3 Vinyl persate 2800 parts, methanol 690
and HS (-CH, +rN (Cf(,) 3C
After placing Q 0 , 005 m in a reaction vessel and purging the inside sufficiently with nitrogen, the external temperature was raised to 65°C, and the internal temperature was 606°C.
When the temperature reached C, 10 parts of methanol containing 185 parts of 2,2-azobisisobutyronitrile was added. Immediately HS B H2'rrN (C)i 3 ) s C(
20 parts of methanol containing 10.02 parts were added uniformly over a period of 2 hours. The polymerization rate after 2 hours was 32%.

After 2 hours, the container was cooled and residual methanol was expelled from the system under reduced pressure to obtain a methanol solution (70% concentration) of vinyl polyversate. To a part of this methanol solution, add a methanol solution of Na0)1 so that the concentration of vinyl polyversatate is 30%, [NaOH] / [vinyl versatate unit] = 0.01 (molar ratio), and 4D It was saponified with 'C to obtain PVA with a saponification degree of 96 mol%.

The degree of polymerization of PVA was measured in the same manner as in Example 1, and was found to be 2,050.

The PVA was washed under reflux with methyl acetate containing a small amount of water, purified by Soxhlet extraction with methanol for 48 hours, then dissolved in heavy water and subjected to NMR analysis.

This confirmed the presence of an ammonium group at the end,
Considering the polymerization mechanism, one end of the molecule is 5kHz'+r.
N(CH3)3c((” 7 P with ammonium group
It was confirmed that it was VA.

The above vinyl polyversatate was partially saponified to obtain a polyvinyl alcohol polymer with a saponification degree of 80 mol%.

Visually measuring the equinox of this 0.4% aqueous solution, it was 83.
℃ and 1 piece.

Examples 4 to 6 In the same manner as in Examples 1 to 3, an amino group, an ammonium group, or a sulfonic acid group was introduced at one end by polymerization using various chain transfer agents, and then by sMR measurement. To make sure. Next, this was saponified to obtain a polyvinyl alcohol polymer.

Roughly, the equinox points of 0.4% aqueous solutions of these polymers were visually measured. The results are shown in Table 1.

Margin below Example 17 In the same manner as Examples 1 to 3, CH.

H3EHI), C0NH-C-C)I, SO3NaH3 is used as a chain transfer agent to polymerize vinyl acetate, and by saponification, a polymerization degree of 2 with a sulfonic acid group at the terminal is obtained.
400, and a polyvinyl alcohol polymer having a saponification degree of 71 mol% was obtained.

The obtained polyvinyl alcohol was dissolved in -DMSO and subjected to NMR analysis, which confirmed the presence of a sulfonic acid group at the end.

The cloud point of a 04% aqueous solution of this polymer was visually measured and found to be 85°C.

Since the polyvinyl alcohol polymer of the present invention has a high clouding point, a uniform aqueous solution can be obtained and its dispersion performance is also high, so that it has extremely high industrial value. Furthermore, the polyvinyl alcohol polymer of the present invention can be used in conventional applications such as paper processing,
It fully exhibits its effects even when used in textile processing, etc.

[Brief explanation of the drawing]

N of the polyvinyl alcohol polymer in Example 17
The MR spectrum is shown in FIG. Patent applicant RiRa Shi Co., Ltd.

Claims (7)

[Claims] (1) A polyvinyl alcohol polymer containing 50 mol% or more of the following structural unit A, a degree of polymerization of 3500 or less, and an amino group, ammonium group, or sulfonic acid group at the end. A: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (2) The polyvinyl alcohol polymer according to claim 1, which contains less than 50 mol% of the following structural unit B. B: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Here, R^1 represents H or a hydrocarbon group with 1 to 20 carbon atoms.) (3) The polyvinyl alcohol polymer according to claim 2, wherein the structural unit B is a vinyl acetate unit. (4) The polyvinyl alcohol polymer according to claim 2, wherein the structural unit B is a vinyl pivalate unit. (5) The polyvinyl alcohol polymer according to claim 1 or 2, wherein the content of structural unit A is 70 mol% or more. (6) A polyvinyl ester polymer obtained by polymerizing vinyl monomers mainly consisting of vinyl ester monomers in the presence of a chain transfer agent having an amino group, an ammonium group, or a sulfonic acid group is saponified. The method for producing a polyvinyl alcohol polymer according to claim 1 or 2. (7) The method for producing a polyvinyl alcohol polymer according to claim 6, wherein the chain transfer agent is a thiol having an amino group, an ammonium group, or a sulfonic acid group.